PI: Zhang, Hui Grant Number: 1RO1AI078812-01A2 Grant title: Effect of cellular microRNAs on HIV-1 replication Revised Abstract Section MicroRNAs (miRNAs) are short ~21-nt-long regulatory RNAs with the ability to repress protein translation. They are involved in the regulation of various biological functions in numerous eukaryotic lineages, including plants, insects, vertebrate, and mammals. Accumulating evidence has indicated that human immunodeficiency virus type 1 (HIV-1) replication is regulated by cell- or virus-derived miRNAs. Recently, we have found that several cellular miRNAs are involved in establishing and maintaining HIV-1 latency in resting primary CD4 T-lymphocytes. The 3'- termini of various HIV-1 mRNAs are the binding site of a cluster of cellular miRNAs including mir-28, mir-125b, mir-150, mir-223, and mir-382, which is enriched in the resting CD4+ T cells rather than in activated CD4+ cells. The antisense inhibitors of these miRNAs can significantly counteract the inhibitory effects of their corresponding miRNAs upon either HIV-1 protein translation in the resting CD4 T-cells transfected with HIV-1 infectious clone, or HIV-1 production from the resting CD4+ T-cells isolated from HIV-1-infected individuals receiving suppressive highly active antiretroviral treatment (HAART). Besides, we have also found that virion associated cellular miRNA could play a role in HIV-1 replication. As the evidence that miRNAs affect HIV-1 replication is solid, we would like to propose the following projects to systematically examine the effect of cellular miRNAs on HIV-1 replication: (1). Mechanistic studies to further clarify how cellular miRNAs contribute to HIV-1 postintegration latency in resting CD4 T-lymphocytes (2). Further investigate the interaction between cellular miRNAs and the inefficient expression of Tat or Rev and their possible synergetic contribution to HIV-1 latency in resting CD4 T-lymphocytes. Experiments in this proposal are designed to provide a detail understanding of the mechanism how cellular miRNAs affect HIV-1 replication. Such information is crucial for further exploiting the relevance of miRNA manipulation in controlling HIV-1 replication and transmission. Following revised aims are proposed for the 2-year ARRA award, which will be followed by a 2-year NIAID award.